Motor gasoline additive



lated based on customer reaction surveys, care- 7,

fully controlled road tests, and laboratory cold- 7 4- 1 case dilution.Howeverfin appreciating the scope of the present invention, it isimportant to note that this invention is only of application to gasroomengine performance tests. :1 These tests;

show that carburetor icing depends primarily upon atmospherictemperature and humidity; The tests show thatstalling diificonditions. Hculties due to ice formation in the carburetor are not encountered belowabout 30F, nor above about 60 F. when employing"fuelshaving'conventional volatility characteristics. Similarly,

these tests demonstrate that stalling is only encountered when thehumidity is in excess of about'65'%. i

Another factor having a bearing onthe formation of ice in' thecarburetor, is the volatility of the fuel-employed- To determine thiseffect, laboratory cold room tests were conducted to evaluate thestalling characteristics during warm-up of a number of fuels varying involatility. In these tests a 1947 Chrysler car was installed in a roomequipped with temperature and humidity controls. While the temperatureand humidity were maintained at particular levels, thestallingcharacteristics of the car were determined during the warm-up period.The procedure'employed was to start the car an then immediately to raisethe engine speed to 1500 R. P. M. This speed was maintained for 30seconds, after which the engine was allowed to idle for seconds. If theengine stalled before 15 seconds had expired, the car was again startedand raised to a speed of 1500 R. P. M. for seconds', while if stallingdid not occur, the speed was immediately increased to 1500 R. P. M.after the 15 second idling time. The alternate cycles of 30 seconds at1500 R. P. M. followed by 15 secends at idling were repeated until theengine was completely warmed up. The number of stalls encountered duringthis procedure, and up to the time of complete engine warm-up were thenrecorded. Tests were conducted at 40 F. and at a relative humidity of100% employing three fuels of varying volatilities. The most volatilefuel was a premium grade of commercial gasoline having a 10% .ASTMdistillation. point of 110 F.,:a point of 190 F., and a point ofv 294 F;Itwas found thatthis fuel resulted in about 14; or 15 stalls duringwarm-up. A medium volatility fuel was also tested, consisting of aregular ,gradecommercial gasoline having ASTM distillationcharacteristics such that 10% distilled at 121 R, 50% distilled at 220F., and distilled at 342 F. The number of stalls encountered with thisfuel were 11. Finally a low volatility gasoline was subjected to thesame test procedure. The "gasoline had ASTM distillation 10, 50, and 90points, at 126 F., 270 F. and 387 F. It was found that 5 stalls wereencountered with this fuel;

" As indicated by these data, carburetor icing is related to thevolatility of the fuel employed. Thus, the least volatile fueltested'above, having a 50% distillation point of 270, only resulted in 5stalls, while the highest volatility fuel, having a 50% distillationpoint of 190 F., resulted in 15 stalls. Extrapolating these data as tothe volatility of the fuel, it appears that a fuel having a volatilitysuch that the ASTM 50% distillation point is 310 F., or higher would notbe subject to stalling difficulties during warm-up. be appreciated,however, that a fuel having It must ASTM distillation characteristics ofthis nature;

would not be desirable as regards warm-up time, cold engineacceleration, economy and crank to gasoline.

oline fuels having an ASTM 50% distillation point below about 310 F. Atthe same time, as will be brought out, it is possible to correlate thequantity of additives required to overcome icing problems with thevolatility of the fuel to be improved. In other words, smallerproportions of additives may be employed with fuels of relatively lowvolatility, while higher proportions of additives may be required withfuels of higher volatility.

As will be brought out by the data which follow, it will be shown thatstalling difliculties may be overcome by employing critical percentagesof dimethyl carbinol together :with diisopropyl ether anda conventionalsolvent oil. Each of these additives contributes to the. solution ofthe. icing problem. The solvent oil, being a. low volatility heavy oil,serves to maintain an oil film over the carburetor parts so as tominimize the adherence of moisture and ice to the carburetor. Thedimethyl carbinol is sufficiently volatile and water soluble to vaporizein the carburetor and to dissolve in moisture. present so as to depressthe freezing point of the moisture. Together then, the dimethyl carbinolsharply lowers the freezing point of moisture in the carburetor whilethe solvent oil decreases the adherence of moisture and ice to thecarburetor. The ether reduces still further the accumulation of ice,apparently through synergistic association with dimethyl carbinol sincethe ether in the absence of dimethyl carbinol has no effect on iceaccumulation. This synergism occurs in the presence or in the absence ofsolvent oil.

It is a .particular feature that by jointly using solvent oil, dimethylcarbinol and the ether, each component contributing a different functionin preventing carburetor icing problems, it is possible to achieve avery high degree of anti-icing with only about 0.5% of solvent oil, notmore than 2.5% of dimethyl carbinol, and from 0.05 to 0.2% of the ether.

.With regard to the solvent oil to be used, this consists essentially ofa liquid hydrocarbon mixture having a kauri-butanol solvent power aboveabout 20, having a 50% distillation point above 350 F., at 10 mm.mercury pressure, having a Saybolt viscosity at F., not above 450seconds, and having an API gravity of about 18 to 28. It is to beunderstood, therefore, that in referring to a solvent oil throughoutthis specification, reference is made to an additive of this nature, asdefined above.

The dimethyl carbinol, or isopropanol, to be employed must be of 98%purity, or greater, although it is preferred that 98% .pure dimethylcarbinol be employed. This chemical is ordinarily produced as crudedimethyl carbinol having a purity of 65%. The 35% of impurities cons stchiefly of water together with small quanties of di-isopropyl ether,higher carbinols and ketones. Use of the crude product of this naturecan not be tolerated, in part since a phase separation would occur onadding the crude product The consequent phase operation would result inan aqueous phase and a gasoline phase containing about 98% pure dimethylcarbinol. It is presently contemplated that, if decontaining dimethylcarbinol of 98% purity. It

is preferred, however, to purify- .the dimethyl carbinolin theconventional manner. to, obtain sub,-

stantially pure dimethyl carbinol. having. less.

than 2% of, water, The. purified, dimethyl carbinol of greater than 98%purity. may. then be blended directly into the gasoline.

As. an aid in understandingtheprinciples of this mixture, itis ofinterest to note that homo-.

logues of dimethyl carbinol. cannot satisfactorily.

be employed. In the case of, higher molecular Weighthomologues, it hasbeen found; that normal propyl carbinol, .iso-propyl carbinol and ethylmethyl carbinol, together withgall, other higher homologues are notsufliciently water soluble to be efiective for suppressingtheformationof care buretor ice. In the case ofv dimethyl carbinol,

apparently sufiicient quantities of .thiscompound.

dissolve in any water condensed in the, carburetorso as to sufiicientlylower the .freezingpoint of 7 this water to prevent ice formation.However, in the case of the higher carbinols, solubility is notsufficient in the water to'permit; this efiect. A furtherconsiderationin this connection isthat it is desirable to employ acompound having as low a molecular weight as possible, to depress thefreezing point of water to the, maximum extent according to Raoults law.However, it has also been found impossible to use. carbinols of lowermolecular weight than dimethyl, carbinol. Thus in the case of carbinol,or methanol, the volatility is such that the compound would notcondenseon the throttle plate of the carburetor, and apparently for thisreason-has little eflect in suppressing icing. Asa furtherconsideration, gasor' line compositions containing carbinol areextremely water sensitive so that the unavoidable contact of gasolinewith water during marketing, or in a car, would result in the loss ofmost, or,

all or the compound. Methyl carbinol, or ethanol, is similarlyobjectionable particularly on.

the basis of Water sensitivity. Thus on contact of any gasolinecomposition containingthese compounds with, for'example, the water whichmay be present in storage tanks; most' of the compounds would be leachedout by the; water. To clearly show this made to data obtained bycontacting gasoline compositions containing, respectively, 2%ofcarbinol, methyl carbinol, and dimethyl carbinol,

with two volume percent of ,Water. Itjwas found a that 81% of thecarbinol was water, while 65% moved, while only was lost.

The compositions embraced within this invention may be more fullyunderstoodby reference to the following examples, which show the effectof solvent oil alone; dimethyl carbinol alone; solvent oil and dimethylcarbinol; and solvent oil, dimethyl carbinol synergistic association.

removed by the of the methyl carbinol was reof the dimethyl carbinolExample I A commercial automotive gasoline was subjected to the coldstartingtests formerly described. This gasoline had the followinginspections:

eifect, reference may be and diisopropyl ether in 10% D+L Fi 134- 50%D-l-L F 209 n+1. ?r 3.05 Reid'vapor pressure 91.2 Gravity i ,API 6. .1

Itwas foundthatthis gasoline-stock result d. in nstaus during thetes'tprocedure;or dnringthe warm-up time of the engine at40F.', and%"relative humidity. 0:5 avolnmmpercent of solvent oil was thenadded tothe gasoline...v This, solven oil-hadthe. followin characteristics:

K'auri'ebutanol; value; 50 distillatiompoint; i413:Say-bolt-..viscosityrat- 1005 FE 75.3 A. Ilgravity; 262.6

1 At 10=1um. Hairless...

It was determined, that s the icingicharacteristics ofithe. carburetorwere improved since warm-up- I was accomplished withgonly-8or:9stalls;

Since the sol'ventoil' is 'sumciently non-volatile to form aliquidgfilm; on: the. carburetor-par i appears that-this film iseffective 'to' decreasethe condensation or adherence-o1 water and ice inthe carburetor. Howeven this effect of solvent oil is apparently notsuitable to eliminate icing problems completely. Thus when thepercentage of solvent oil in the gasoline of this example was doubled,no appreciable zimprovement;in enginezoperation was obtained. Sowhilethe-liquid-film forming eifectof solvent oilmayberelied-ron to'decrease icing, problems, resort-must;- be hadEtO- other agents to coactwith. thesolvent; oil; to completely eliminate icing difiiculties;-

Data of the nature indicatedin.this-example therefore shows thatabout;0.5%. 0f;;1s olvent;oi1, improve 7 unsatisfactory carburetor,icing; and:

is suficient to materially. engine operation due to that use of greaterproportions. provideslittle if any incremental improvement. It ispreferred that the. quantity .of solvent. oil; should .not-exceed about0;.5

volume-since changes distillation or, volatility characteristics ofgasoline when presentinan-y substantial portions, and-since. it. also;adversely. changes-the. octane number of therfuel. gum test inspections.

Example 2 To the base gasoline employedriniExamplerl, 1% of 99% dimethylcarbinol=wasladdedx It :was found that the number" during warm-upwith.this: fuelztcomposition hadbeen reduced from a control:value:ofabout=1l to about 6. These data, therefore; indicate that 1 of dimethylcarbinol is sufficient-to eifect an appreciable improvement in thecarburetor icing characteristics of a'base gasoline.

Example. 3:

In. understanding this coaction,.it..is .,helpful to realize that atleast. a portionofthedimethyl carbinol will be maintained solution imthefilm of solvent: oil. The solvent oilthus has the it .materially and.the. copper. dish.

of t stalls: encountered point where it is needed. I

' Example 4 To determine the efiect of employing small quantities ofsolvent oil and dimethyl carbinol in gasoline, experiments wereconducted with a gasoline containing 0.5 volume percent of solvent oiland 0, 1, and 2% of dimethyl carbinol. The base fuel employed,consisting of a premium brand commercial gasoline containing 0.5%solvent oil and 1.38 cc. per gallon of lead tetraethyl which will beidentified as Fuel Base A, had the characteristics indicated in thefollowing Table 2. Also indicated in the table are the characteristicsof this fuel base plus 1 and 2 volume percent of 99% pure dimethylcarbinol.

TABLE 2 Fuel A Containing 0.5% Solvent Oil Vol. Percent (99% DimethylCarbinol) 1 2 ASTM Distillation, I. B. P., F 84 86 87 F. for 10% D+L 110106 105 F. for 50% D-i-L 190 190 187 F. for 90% D+L 294 293 292 PercentD-l-L (a) 158 F. 34. 5 35.0 37. 5 Reid Vapor Pressure, p. s. 13.2 12. 812.3 Gravity, API 66.3 66.0 85. 7 General Motors Gum, mgJlOD ml 0.8 0.82. 2 Copper Dish Gum, rug/100 ml 276 251 238 ASTM Breakdown, Minutes.454 300 338 Motor Octane Numbcr.- 82. 2 82.0 82. 2 Research OctaneNumben 01. 4 91. 0 91. 7 Lead Content, ccjgal 1 38 1. 37 1.35

It will be noted from this table that addition of 1 and 2% of dimethylcarbinol to the base fuel stock containing the solvent oil does notadversely affect the inspections of the fuel. It is significant thateven at 2% concentration, suflicient dimethyl carbinol was not presentto affect the octane rating of the fuel outside of the experimentalerror involved in octane determinations.

.Laboratory cold room tests were then conducted according totheafore-described procedure to determine the carburetor icingcharacteristics of a car containing the fuel compositions of Table 2.Results of these tests are given in Table 3. By way of explanation, itmay be noted that the temperature and humidity conditions of the testwere chosen as being the most severe which could be encountered asregards stalling tendency. Thus, by the nature of tests formerlyindicated involving consumer reaction, laboratory tests, and road tests,it was determined that engine stalling occurs most frequently at atemperature of about 40 F., when the humidity is relatively high.

TABLE 3 Laboratory tests-1947 Chrysler :Referring to Table 3, it will benoted that the base fuel identified as Fuel A and containing 0.5% ofsolvent oil Was subject to an average of about 14.5 stalls during thewarm-up time, at a humidity of 100%. The frequency of stalls wassomewhat less at the lower humidity levels of and 80%; When 1% ofdimethyl carbinol was added to Fuel A, it was found that no stallingoccurred at relative humidities below about and thateven at relativehumidity, only about 2 stalls occurred during warm-up. Finally, it willbe noted that addition of 2% and 2.5% of dimethyl carbinol effected agreater improvement in stalling causing the frequency of stalls to berespectively about 1 and about 0.5 during warm-up; and further limitingthe humidities at which stalling could occur to relative humidities ofabout 99%, or greater. The data of Table 3, therefore, fullydemonstrates the advantageous characteristics of the compositions ofthis invention. That is, the data show that a gasoline fuel containing0.5 volume percent of solvent oil, and from about 1.0% to 2.5% ofdimethyl carbinol is substantially free of stalling tendencies.

The indicated compositions are completely free of adverse carburetoricing below relative humidities of 95%, and at 2% concentrations ofdimethyl carbinol do not permit stalling at relative humidities below99%. In addition, these fuel compositions under the most adverseconditions would not be subject to stalling except in an extremelynarrow temperature region. Thus with the 1% dimethyl carbinol blend,carburetor icing would ordinarily not occur except at relativehumidities above 95%, and then only when ambient temperatures are in therange of about 38 F. to 42 F. It should further be noted in connectionwith the data of Table 3, that Fuel A employed in this table is arelatively high volatility fuel having a 50% distillation point of F.This volatility is such that the commercial gasoline having thisvolatility is ordinarily described as approaching the volatility Icharacteristics of aviation fuels. Consequently, in extrapolating thedata of Table 3, to regular brand gasolines having lower volatility itis apparent that addition of 0.5% solvent oil and from 1 to 2% ofdimethyl carbinol is effective in substantially eliminating carburetoricing difficulties.

From the foregoing it is apparent that improved fuel compositions aresecured when utilizing an alcohol, particularly dimethyl carbinol inconjunction with a solvent oil. It has now been discovered that a"further improvement is secured provided a relatively small amount ofdiisopropyl ether be utilized in conjunction with thehydrocarbon-alcohol mixture. In accordance with the present invention,it is preferred to use from 0.5 to 2.5% by volume (based upon the motorfuel) of a low molecular weight alcohol, particularly dimethyl carbinolin a motor gasoline and to use in conjunction with the low molecularweight alcohol from .05 to 0.2% by volume (based upon the motor fuel) ofan ether. particularly diisopropyl ether.

The'present invention may be more fully appreciated by the followingexample illustrating the same.

Example 5 In a series of carburetor icing tests, blends containingdimethyl carbinol and diisopropyl ether in a motor fuel of the type ofpremium igradezmotor gasoline and containing abQut'i0'5% selvent wereused. 'sumgasonnemcrmauy contains ethyl fluid" corresponding to'b'etween1 and 3 cc. dftetraethyl 'leadpfl gallon of gasi olineiand normallyhasfiatil-east 80 octane num- --:ber. Agasoline having'caniinit-ialboilinggpoint 60% distilled at 212 F., and about 90% distilled at 302 F.by ASTM Method 13-86, was mixed with various percentages of dimethylcarbinol and diisopropyl ether and the icing characteristics of thefuels were determined. The fuel was carbureted by air saturated withwater at about 40 F., employing an air-fuel ratio of about 12/1 byweight. The minutes of elapsed time prior to the first indication of iceformation on the carburetor throttle plate are shown in Table 4.

TABLE 4 Carburetor icing tests Volume Percent Time to Initial IceFormation, Dimethyl Diisopropyl Mins.

Garbinol Ether Example 6 In another series of tests, a mixturecontaining about 92% dimethyl carbinol, 6% diisopropyl ether and 2%water by volume was added in various proportions to a gasoline similarto that employed in Example 5 and containing about 0.5% of solvent oil.The icing characteristics of the resulting blends, as determined in thecarburetor icing apparatus, are shown in Table 5.

TABLE 5 Carburetor icing tests Volume Percent:

Dimethyl Oar- Time to Initial binol, Diisopro- Ice Formation, pyl EtherMix- Minutes ture None 0.7 0.5 0.6 1.0 0.8 1.5 5.1 2.0 10+ The data showthat decidedly superior results are obtained by employing dimethylcarbinol, diisopropyl ether and solvent oil in particular proportionsand in particular concentrations.

It is apparent that the fuel compositions falling within the scope ofthis invention may include any of the commonly used gasoline additives,such as lead alkyl anti-detonants, lead bpesfsae scavenging.agents,,1dyes, lgum'finh'ibitors, oxidation inhibitors, .etc.LItlisparticularly-contemplated that i metal. deactivators andl-rlustpreventives may be included in th'eiuel. N;N.' -disa'li- "cylal-fl;2-diamin'o propane,fiand"N;N'disalicylal- '1,2-diamino ethane areexampiesbrsuitabiemeta1. deactivators. sorbitan monoleate,pentae'rythritolLl-inonoleateiand phosphates, nitrates, and nitritessuchas "the amine phosphates, nitrates, andnitrites are examples ofsuitable .rus t :preventiveswhich may be used. It is apparent that thisinvention-"is oi"application't'o -any gasoline fuel ba'se having avolatility isuch thatzthez'% distillaticnipoint .falls..below. about310E2E1l ifli'he gasolines thus include automotive type gasolines,marine type gasolines, and aviation gasolines.

What is claimed is:

1. A composition consisting of a mixture of hydrocarbons boiling in thegasoline boiling range and containing from about 1.0 to 2.5% by volumeof dimethyl carbinol and from about .05 to 0.2% by volume of diisopropylether.

2. Composition as defined by claim 1 wherein said composition containsabout 0.5% by volume of a solvent oil.

3. A composition consisting essentially of a mixture of hydrocarbonsboiling in the gasoline boiling range and containing about 0.5 volumepercent of solvent oil, from about 1.0 to 2.5% by volume of dimethylcarbinol and from about .05 to 0.2% by volume of diisopropyl ether, saidsolvent oil consisting of a liquid hydrocarbon mixture having akauri-butanol solvent power above about 2-0, a distillation point aboveabout 50 F. at 10 mm. mercury pressure, a Saybolt viscosity at 100 F.,not above 450 seconds, and an API gravity of about 18 to 28.

4. The composition of claim 3 in which the concentration of the saiddimethyl carbinol is 2.0%.

5. The composition of claim 3 in which the said dimethyl carbinolconsists of at least 98% pure dimethyl carbinol.

6. A gasoline composition including 0.5% by volume of solvent oil and1.9% by volume of 98% pure dimethyl carbinol and 0.1% by volume ofdiisopropyl ether.

7. The composition defined by claim 6 in which the mid-boiling point ofthe said mixture of hydrocarbons boiling in the gasoline boiling rangeis below about 310 F.

8. The composition defined by claim 6 in which the said mixture ofhydrocarbons boiling in the gasoline boiling range has a mid-boilingpoint of about 190 F.

9. The method of operating an internal combustion engine in moist, cooltemperature conditions which comprises burning a. gasoline fuel in thesaid engine containing about 0.5% of solvent oil, 1.9% of dimethylcarbinol of at least 98% purity and about 0.1% of diisopropyl ether,said solvent oil consisting of a liquid hydrocarbon mixture having akauri-butanol solvent power above about 20, a 50% distillation pointabove 350 F., at 10 mm. mercury pressure, a Saybolt viscosity at 100 Fnot above 450 seconds, and an API gravity of about 18 to 28.

10. The method of improving the combustion of a gasoline fuel at ambienttemperatures between 30 and F., and employing air having relativehumidities greater than about which comprises burning said gasoline fueland said air in the pressure of about 0.5 volume percent of solvent oiland 1.9% of dimethyl carbinol based on the quantity of gasoline,and--about 0.1% 01' diisopropyi ether said solvent oil consisting of a,liquid hydrocarbon mixture having about 18 to 28".

JOHN E. I-IICKOK.

JOHN A. RYAN.

References Cited in the file of this patent UNITED STATES PATENTS NameDate Bue June 30, 1936 Number 2.046.243

Number Number 12 Name Date Hooton Aug. 29, 1941 Neudeck Dec. 25, 1951FOREIGN PATENTS Country Date Great Britain 1938

9. THE METHOD OF OPERATING AN INTERNAL COMBUSTION ENGINE IN MOIST, COOL TEMPERATURE CONDITIONS WHICH COMPRISES BURNING A GASOLINE FUEL IN THE SAID ENGINE CONTAINING ABOUT 0.5% OF SOLVENT OIL, 1.9% OF DIMETHYL CARBINOL OF AT LEAST 98% PURITY AND ABOUT 0.1% OF DIISOPROPYL ETHER, SAID SOLVENT OIL CONSISTING OF A LIQUID HYDROCARBON MIXTURE HAVING A KAURI-BUTANOL SOLVENT POWER ABOVE ABOUT
 20. A 50% DISTILLATION POINT ABOVE 350* F., AT 10 MM. MERCURY PRESSURE, A SAYBOLT VISCOSITY AT 100* F., NOT ABOVE 450 SECONDS, AND AN API GRAVITY OF ABOUT 18 TO 28*. 